Knowledgebase

Firewall is the first line of defense for server security, and proper configuration is essential.

Linux Firewall (firewalld):

Check Status:

systemctl status firewalld

Start the Firewall:

systemctl start firewalld
systemctl enable firewalld

View Open Ports:

firewall-cmd --list-ports

Open Ports:

firewall-cmd --permanent --add-port=80/tcp
firewall-cmd --permanent --add-port=443/tcp
firewall-cmd --permanent --add-port=22/tcp

Close a Port:

firewall-cmd --permanent --remove-port=8080/tcp

Reload Configuration:

firewall-cmd --reload

Linux Firewall (iptables):

View Rules:

iptables -L -n

Open a Port:

iptables -A INPUT -p tcp --dport 80 -j ACCEPT

Save Rules:

service iptables save